The invention relates to a device and a method for generating a phase-shifted, in particular phase-delayed, output signal from an input signal, in particular for use in micro electronics.
In micro electronics, delay synchronization loops (‘Delay Locked Loops’; DLLs) are used to generate a clock signal derived from a reference clock signal with a predetermined fixed relative phase relationship.
Known DLLs include a delay line constructed of cascaded identical delay elements, the delay line being fed by the reference clock signal via a buffer. A phase discriminator that usually checks for 180° phase shifting compares the phase relationship of a signal at the beginning and of an inverted signal at the end of the delay line. If a phase difference exists, control information is generated to adjust the delay of the delay elements. As soon as the feedback loop has converged, i.e. the signals have been synchronized, a phase difference of 180° or 180° +n·360°, respectively, is present between the beginning and the end of the delay line. By a control information regulation algorithm, n=1, 2, 3, . . . is usually set. Between the delay elements, phases with a corresponding offset can be tapped by means of a multiplexer and be output as a derived clock signal. Due to the construction as a feedback loop, all changes of the method parameters, voltage, or temperature (which all change the delay of the delay elements) are compensated for to the extent that they relate to the entire delay line. However, there exist two intrinsic non-compensated delay components: both the buffer and the multiplexer include a propagation delay. Thus, a phase shifting between the reference clock signal and the clock signal derived therefrom occurs even if a phase of 0° is set by the multiplexer. Another problem is that the intrinsic delay is completely dependent on the manufacturing process, the voltage, and the temperature. If the resolution is to be increased, the delay of the multiplexer that is necessarily also larger will also be increased.
For these and other reasons, there is a need for the present invention.